J = kW × 1,000 × seconds
A watt is a joule per second, so watts × seconds = joules.
A 2 kW load running for 30 seconds transfers 60,000 joules. The joule is a small unit, which is exactly why the prefixes matter so much here.
kW to Joules
Convert power into joules, the SI unit of energy, for physics work and instrumentation.
Need the power figure before the energy figure? Work it out with the kVA to kW converter first.
kW to Joules Calculator
J = kW × 1,000 × seconds2 kW
kW
30 s
s
Quick values
At a glance
J = kW × 1,000 × seconds
- Energy
- 60,000 J
- Power
- 2 kW
- Duration
- 30 s
Every diagram and table on this page updates with the calculator above.
Output
Live60,000J
J = 2 kW × 1,000 × 30 s = 60,000 J
In kilojoules60 kJ
In kilowatt-hours0.0167 kWh
The kW to Joules Formula
The conversion
LiveInput2kW
Result60,000J
Why the Joule Sits at the Centre of SI
The joule is the SI unit of energy in every context — mechanical, electrical, thermal and chemical. That universality is its whole point: one newton-metre, one watt-second and one coulomb-volt are all the same joule.
| Definition | Expression | Domain |
|---|---|---|
| Work done by a force | 1 N × 1 m | Mechanics |
| Power over time | 1 W × 1 s | Electrical |
| Charge through a potential | 1 C × 1 V | Electrical |
| Heat added | 1 kg × 1 K × specific heat | Thermodynamics |
The joule is deliberately small
Lifting an apple one metre takes about one joule. Real engineering quantities therefore live in kJ, MJ and GJ.
Energy magnitude
Live1 kJ
100 kJ
10 MJ
1 GJ
60,000 J
Watching Joules Accumulate
Energy is the area under a power-versus-time curve. For a steady load that area is a rectangle, and the arithmetic is a single multiplication.
For a varying load the principle is identical — you integrate rather than multiply, which is precisely what an energy meter does in hardware.
Accumulating energy
LiveEnergy delivered60 kJ
kW to Joules Conversion Chart
Your power level held for a range of durations, in joules and kilowatt-hours.
Conversion chart
Live| s | Energy (J) | Energy (kWh) |
|---|---|---|
| 1 s | 2,000 | 0.0006 |
| 5 s | 10,000 | 0.0028 |
| 10 s | 20,000 | 0.0056 |
| 30 s | 60,000 | 0.0167 |
| 60 s | 120,000 | 0.0333 |
| 120 s | 240,000 | 0.0667 |
| 300 s | 600,000 | 0.1667 |
| 600 s | 1,200,000 | 0.3333 |
| 1,800 s | 3,600,000 | 1 |
| 3,600 s | 7,200,000 | 2 |
Joules in Mechanical Work
Because the joule spans domains, an electrical figure converts directly into a mechanical one. This is how you check whether a motor is big enough to lift a load in the time available.
J = mass (kg) × 9.81 × height (m)
Potential energy gained when lifting a mass against gravity.
A hoist lifting 500 kg by 12 m
Given
- Mass: 500 kg
- Height: 12 m
- Time available: 30 s
- Efficiency: 75%
Working
- Energy = 500 × 9.81 × 12 = 58,860 J
- Input energy = 58,860 ÷ 0.75 = 78,480 J
- Power = 78,480 ÷ 30 = 2,616 W
You need about 2.6 kW of motor power, before allowing for acceleration and friction.
Joules against power
Live2 kW60,000 J
Joules, kWh and Calories
| Unit | In joules | Typically used for |
|---|---|---|
| 1 J | 1 | Physics and instrumentation |
| 1 calorie | 4.184 | Thermochemistry |
| 1 kcal (food Calorie) | 4,184 | Nutrition labels |
| 1 BTU | 1,055 | HVAC in imperial markets |
| 1 kWh | 3,600,000 | Electricity bills |
| 1 therm | 105,500,000 | Gas billing in some markets |
3.6 MJoules in one kWh
1,055Joules in one BTU
4.184Joules in one calorie
Three durations
Live1 second
- Joules
- 2,000 J
- kWh
- 0.0006
1 minute
- Joules
- 120,000 J
- kWh
- 0.0333
1 hour
- Joules
- 7,200,000 J
- kWh
- 2
Every Power Converter in One Place
29 calculators built on the same maths as the tool above. Each one has its own inputs, interactive diagrams and worked examples.
kW to kVA
kVA = kW ÷ PFkVA to MW
MW = kVA × PF ÷ 1,000kVA to MVA
MVA = kVA ÷ 1,000VA to kVA
kVA = VA ÷ 1,000VA to kW
kW = VA × PF ÷ 1,000kVA to Watts
W = kVA × 1,000 × PFkW to Watts
W = kW × 1,000kW to GW
GW = kW ÷ 1,000,000kVA to kW (Single Phase)
kW = kVA × PFkVA to Amps
A = kVA × 1,000 ÷ (V × √3 for 3-phase)kVA to Amps (Three Phase)
A = kVA × 1,000 ÷ (√3 × V)Amps to kW
kW = √3 × V × A × PF ÷ 1,000kW to Volts
V = kW × 1,000 ÷ (√3 × A × PF)kW to kWh
kWh = kW × hourskW to MWh
MWh = kW × hours ÷ 1,000kW to GJ
GJ = kW × hours × 0.0036kW to kJ
kJ = kW × secondsCurrent
kW to Joules
J = kW × 1,000 × secondskW to HP
hp = kW × 1.34102kW to BHP
bhp = kW × 1.34102kW to Nm
N·m = 9549.3 × kW ÷ rpmkW to Torque
T = 9549.3 × kW ÷ rpmkW to RPM
rpm = 9549.3 × kW ÷ N·mkW to CC
cc = (kW ÷ kW per litre) × 1,000kW to BTU/hr
BTU/hr = kW × 3,412.142kW to Ton
TR = kW ÷ 3.51685kW to GPM
GPM = BTU/hr ÷ (500 × ΔT)kW to CFM
CFM = BTU/hr ÷ (1.08 × ΔT)kW to PSI
bar = kW × η × 600 ÷ L/minkW to Joules Questions
Common questions about converting kw to joules.
A kilowatt delivers 1,000 joules every second. Over one hour that is 3,600,000 joules.
Multiply by 1,000 to get watts, then by the duration in seconds: J = kW × 1,000 × s.
Energy. The watt is the unit of power, defined as one joule per second.
3.6 million joules, or 3.6 MJ.
A month of household use would run to tens of billions of joules. Kilowatt-hours keep the figures readable.
4,184 joules. A nutritional Calorie is a kilocalorie, which is why the numbers look so large next to physics calories.